Polyacylurethanes are known in the art and have a distinct advantage over conventional polyurethanes in that the monomer diacylisocyanate have activated isocyanate groups due to the adjacent carbonyl group. The activated isocyanate groups appear to be more reactive towards activated hydrogen atoms, e.g. hydroxyl groups, and show a higher propagation rate in chain extension processes. Moreover, diacylisocyanate monomers can easily and safely be prepared since no phosgene is necessary. A process for the manufacture of these monomers is inter alia disclosed in U.S. Pat. Nos. 4,769,485 and 5,386,057, both incorporated by reference herein.
The synthesis of polyacylurethanes is also known in the art and involves two general processes. The first process is disclosed in e.g. U.S. Pat. No. 5,556,933, incorporated by reference herein, and involves the polymerisation of acylcarmabates having the following general formula:
wherein R1 is an alkylene group, preferably an alkylene group having a molecular weight of 28 to 30,000, wherein the alkylene group may contain an alicyclic group, an aromatic group or an oxygen atom, R2 is an alkylene group, an arylene group or an alkenylene group having 1-8 carbon atoms and R3 is an alkyl or aryl group having 1-18 carbon atoms that may also contain an oxygen atom. In a preferred embodiment, R1 is derived from a diol including low molecular weight, oligomeric and high-molecular weight diols such as diols having a number average molecular weight of preferably 300 to 3000. Examples that are mentioned in U.S. Pat. No. 5,556,933 include polycaprolactone diol, polytetrahydrofuran diol and polydimethylsiloxane diol. The polyacylurethanes are prepared from the monomer shown above in the absence of a solvent and a catalyst and have a molecular weight of 500 to 100,000 (example 6 discloses the highest Mn of 48,000). The polyacylurethanes are said to be useful in various industrial applications such as a modifier for a hydroxyl group containing material, a high functional coating composition and an adhesive. However, tensile properties are not disclosed.
The second process is disclosed in e.g. Polymeric Preprints Japan, Vol. 42, No. 6, pages 1922-1924 (1993)—cf. U.S. Pat. No. 5,555,933, column 1, lines 46-47—and involves the polycondensation of a diacylisocyanate and a diol leading to polyacylurethanes having a structure different from the polyacylurethanes disclosed in U.S. Pat. No. 5,556,933:
wherein R and R′ are hydrocarbyl groups. Again, tensile properties are not disclosed.
JP 6228268 discloses a similar process, i.e. the polymerisation of diacylisocyanates (wherein X contains less than 40 carbon atoms and may be substituted alkylene, substituted cycloalkylidene such as terephthaloyl diisocyanate) with diols (wherein Y is alkylene) to polymers having a number average molecular weight of 1000 to 10,000. JP 6228268 is silent about tensile properties.

Likewise, Endo et al., Macromolecules 27, 3694-3697, 1994, disclose the synthesis of polyacylurethanes wherein isophthaloyl diisocyanate, terephthaloyl diisocyanate or 5-t-Bu-isophthaloyl diisocyanate are reacted with aliphatic diols, e.g. 3,3-dimethyl-1,5-pentane diol. The polyacylurethanes obtained have a number average molecular weight in the range of about 10000 to about 20000 and glass transition temperatures in the range of about 65° to about 145° C. Endo et al. also disclose the reaction between isophthaloyl diisocyanate and poly(tetramethylene oxide) having a number average molecular weight of about 750 which provided a polyacylurethane having a number average molecular weight of about 23000. Endo et al. does not disclose that the polyacylurethanes have elastomeric properties.
U.S. Pat. No. 4,608,420 discloses a process wherein N-alkylcarboxy imides are reacted with for example polymeric diols according to the following equation, wherein R is a hydrocarbyl radical having 2-10 carbon atoms, R′ may be e.g. be alkyl having 3-10 carbon atoms and R″ is derived from e.g. a polymeric diol:
U.S. Pat. No. 4,608,420 does not disclose tensile properties either.